Method and apparatus for rolling steel material and rails or similarly shaped products

ABSTRACT

A method and apparatus for rolling steel material into steel products having flanges such as rails and H-shaped products by use of a universal rolling mill wherein the cross section along the direction of axis of the vertical roll of the universal rolling mill has a convex shape. Therefore, the rolling by such vertical roll gives a reduction of nearly V-shaped concentration to the part of the steel material contacting said vertical roll and to be made into a flange.

United States Patent [72] Inventors Koe Nakajima;

llisashi Nani; Kanichi Kishikawa; llidehiko Abe; Kazunari Tanaka, all of Kitakyushi, Japan [21 1 Appl. No. 790,766 [22] Filed Jan. 13, 1969 [45] Patented Aug. 10, I971 [73] Assignee Nippon Steel Corporation Tokyo, Japan [32] Priority Jan. 16, 1968 [33] Japan [3| 43/2,2l3

[54] METHOD AND APPARATUS FOR ROLLING STEEL MATERIAL AND RAILS 0R SlMlLARLY SHAPED PRODUCTS 4 Claims, 13 Drawing Figs.

[52] U.S.Cl. 72/225 [51] lnt.Cl. B2lb 13/10 [50] Field of Search 72/224,

Primary Examiner- Milton S. Mehr At!0rney Wenderoth Lind and Ponack ABSTRACT: A method and apparatus for rolling steel material into steel products having flanges such as rails and l-l-shaped products by use of a universal rolling mill wherein the cross section along the direction of axis of the vertical roll of the universal rolling mill has a convex shape. Therefore, the rolling by such vertical roll gives a reduction of nearly V- shaped concentration to the part of the steel material contact ing said vertical roll and to be made into a flange.

Patented Aug. 10, 1971 3,591,954

4 Sheets-Sheet 1 FIG. I PRIOR ART 5 7 5 i f I E FIG. 2 PRIOR ART KOE NAKAJIMA, HISASHI NAOI,

KANICHI KISHIKAWA,

HIDEHIKO ABE and KAZUNARI TANAKA,

INVENTOR. S

BYMWMM Attorneys Patented u 10, 1971 3,597,954

4 Sheets-Sheet 2 FIG. 3A PRIOR ART tuvwxyz FIG. 3B PRIOR ART" O b c d e 'FIG.;.4A m 45 KOE NAKAJIMA, HISASHI NAOI, KANICHI KISHIKAWA, [IIDEHIKO [\BE' and I KAZUNARI TANAKA,

INVENTOR. 5

Attorneys Patented Aug. 10, 1971 4 Sheets-Sheet 5 KOE NAKAJIMA,

HISASHI -NAOI, KANICHI KISHIK IIIDEHIKO ABE a 'NVENTOR-b KAZUNARI TAN/\KA,

abbit/flaw Attorneys Patented Aug. 10, 1971 4 Sheets-Sheet 4 i 6 U i a I (V2)[E|l (V3) IL '6' L HIDEHIKO ABE and KAZUNARI TANAKA,

INVENTOR Attorneys METHOD AND APPARATUS FORROLLING STEEL MATERIAL AND RAILS OR SIMILARLY SHAPED PRODUCTS BACKGROUND OF THE INVENTION 1. Field ofthe Invention The present invention relates to a method and apparatus for rolling a steel material into rail or similarly shaped product such an H-shaped steel product or an l-shaped steel product by the universal rolling mill.

2. Description of the Prior Art It is widely known that the rolling of steel material into products having flanges such as rails, H-shaped steel products,

I-shaped steel products and T-shaped steel products by the conventional pass rolling methods, becomes more difficult as the cross section ofsuch products becomes larger.

In order to overcome difficulties arising from the size of the rolled products, particularly when large as mentioned above, the conventional methods have been superceded by a rolling method using the universal rolling mill having vertical rolls as well as horizontal rolls.

The rolling by such universal rolling mill has the merit of forming the head, particularly of a rail which requires forging to a great degree, concentrically by the vertical rolls. That is, the surface of the head of the rail which contacts wheels, is required to meet the most severe conditions, compared with the other parts, and therefore, the concentrated forging of the surface of the head of rail is an important factor for the prolongation of the life of the rail as well as for the prevention of breakage which might cause accidents.

Also, concerning H-shaped steel products and I-shaped steel products of the ordinary type, increased forging of flanges is required the in view of the demand for increased strength as construction material. Though, as mentioned above, the universal rolling mill can concentrically forge the head of rail, even such concentrated forging leaves certain parts unforged (hereafter referred to as the "unforged zone). This causes poor quality of product and the resulting complications, which constitutes an unavoidable problem in making rails and similarly shaped products by the universal rolling mill.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for rolling a steel material into steel products having flanges such as rails, H-shaped steel products and I-shpaed steel products by the universal rolling mill, without the formation of the unforged zone on the flanges of the products, such as the head of the rail.

The special characteristic of the present invention lies in the improvement of the method for rolling steel material into a shaped steel product having flanges such as a rail or an H- shaped steel product by the universal rolling mill and also the improvement of the universal rolling mill per se, whereby the cross section along the direction of the axis of the vertical roll of said universal rolling mill has a convex shape, Therefore, the rolling by said vertical roll gives a reduction of V-shaped concentration to the central part of the steel material contact ing said vertical roll.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 illustrates the rolling ofa rail according to the conventional method using the universal rolling mill; FIG. 2 illus trates the operation of edger rolls set before and behind the ing metal flow while rolling a roughly preformed steel piece of the same source as the piece of FIG. 3A, and FIG. 4B the condition of the metal after the rolling is finished; FIG. 5 illustrates the operation of the vertical rolls ofthe universal rolling mill on the head of rail according to the present invention; FIG. 6 illustrates the rolling according to the rolling method of FIG. 1; FIG. 7 exemplifies the modification of the rolling according to the present invention, showing the distribution of the same pressure when the vertical roll has only one convex part; FIG. 8 to FIG. I0 illustrates the rolling by the universal rolling mill according to the present invention, ofwhich FIG. 8 shows that at first stage, FIG. 9 that at the middle stage and FIG. 10 that at the last stage; and FIG. 11 is a sketch of the overall process according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The following is the description of the preferred embodiment of the present invention using as an example of the rolling on a rail according to the present invention, compared with the conventional method.

FIGS. 1 and 2 illustrate the rolling ofa rail using the universal rolling mill, as carried out conventionally.

By passing through a predetermined space between a pair of the horizontal rolls 1 and 2 and a space between the vertical roll 3 having the rolling pass shaped similarly to the head of the rail and the vertical roll 4 rolling the material from the direction of the part ofthe material to be made into the foot of the rail, the to-be-rolled material is reduced in the thickness of the head 5, of the web 6 and of the foot 7. In next step, as shown in FIG. 2, the material passes through a predetermined space between the horizontal rolls 8 and 9 (the so-called edger rolls"); which passage is for the formation of the widths of the head and of the foot; the combination of the above rollings being carried out repeatedly until the desired sizes of the final product are obtained.

However, the rolling carried out by the conventional method, as mentioned above, is found to cause certain complications resulting in a poor quality product, which complications arise from the formation of an unforged zone in the surface ofthe head. This is due to the clinging ofthe object rolled by the hot rolling mill. The unforged zone does not contribute to extension or deformation of the material, even though a great reduction overall is obtained by such method.

FIGS. 3A .illustrate the formation of the unforged zone, presenting theobservation of metal flow of product when rolled by the rolling method of FIGS. I and 2, using an assumed network on the cross section of the roughly preformed steel piece. By this observation it is found that, compared with the central part, the surface part has some squares the height of which remain as high as before rolling, proving that the surface part was scarcely extended. Such zone is shown with oblique lines in FIG. 38 though it does not exist actually with such a distinct boundary. The area of the oblique lines varies according to ratios of the thickness and the width of the material, reductions, etc.

The presence of such unforged zone causes complications during rolling operations, resulting in poor quality or breakage of product, as follows:

I. The presence of such unforged zone necessitates a great reduction in load. More in detail, when comparing the reductions H of thickness H of the material with and without the presence of the unforged zone having a thickness I, the reduction rate of the latter case is represented by AH/H, and that of the former by AH/H l. Such comparison makes it clear that in order to obtain a reduction of AH, the former case required a greater reduction rate, and a correspondingly greater reduction load than the latter case.

2. Distortion of the to-be-rolled material may occur due to the difference in extension rate between the surface part containing the unforged zone and other parts.

3. Defects may be produced.

4. As it is impossible toquantitatively determine the influence of the presence of the unforged zone on the extension rates of the head, web and foot, it is difficult to balance reductions among them.

5. As the extension rate of the surface part is small, uneven deformation tends to occur from one place to another of the same cross section, producing residual stress.

6. Also due to the above-mentioned uneven deformation, shearing stress is produced on the boundary line, causing such difficulties as crack and breakage of the product by impact while in use.

The present invention is based on the finding that the modification ofthe shape ofthe rolling pass ofthe vertical roll can eliminate the unforged zone.

FIG. 5 shows the head ofrail deformed by the vertical roll of part ofthe head ofrail 5 having a convex shape.

Thus, the unforged zone produced in the head of the rail is subjected to concentrated reduction by said convex part ofthe vertical roll, resulting in enforced rolling ofthe unforged zone.

This operation condition is clearly illustrated in H0. 4A and B. In this case was used a roughly preformed steel piece of the same source as that used in the rolling of FlGI3A. FlG. 4A shows metal flow while rolling said steel piece into the head of present inven tion provides an improved effective rolling method. If a rail having a very broad head is to be made, the vertical roll may be provided with two or more convex parts, so as to eliminate the unforged Zone more effectively.

However, for complete elimination of the unforged zone as shown in FIG. 4B, restriction in the direction of width of the rail must be considered, as well as the provision of one or more convex parts.

In the rolling ofa rail by the universal rolling mill, particu larly for the strong forging of the corner part B of the head of the rail FIG. 5, it is reportedly important that the vertical roll of the universal rolling mill and the edger rolls set before and behind it should maintain contact with said corner part B during the entire rolling operation. This, of course, causes the extension of the material in the direction of the width to be restricted.

part of the vertical roll is the unforged zone is not convex part of the vertical roll with the central part of the head of the rail when generally positioned above the surface of the roll table. and pushes up against the tip ofthe to-be-rolled material as carried over by the roll table and charged into the rolling mill.

Therefore, in order to avoid such misalignment taking place when the rolls contact the material, a restriction to some the direction of the width is required.

sive restriction to the extension of the material in the direction ofthe width.

According to the present invention, it is desirable to provide such universal rolling mill at as early stage of the process as possible, since the rolling pass used at the middle stage should profile as nearly resembling the shape of the final as possible. This is true since the formation of a conthat at the middle stage, and stage.

According to the present invention, there are provided edger rolls of the ordinary type before and behind the universal rolling mill, as illustrated in FlG. H.

The vertical roll 10 of the universal rolling mill used at the early stage of rolling has the rolling pass shaped like the letter which concentrically reduces the whole of the part of the to-be-rolled material 6-! to be made into the head. At the same time, the thickness of the part to be made into the web and of the part to be made into the foot are reduced respectively by a pair of the horizontal rolls 1 and 2 and the vertical roll (11).

At the middle stage, the material which has passed through the previous stage, is subjected to reduction on the part to be concentration but since has been sufficiently forged, and the tip D, of the concave part corresponding to the corner part of the tioned restriction ofextension in the direction ofthe width; for example, if the taper for D,E is l/Z, that for IE is made l/2 l/l.5 and that for i H1.

FIG. 11 shows one example of the overall rolling apparatus the material is carried out by the universal rolling mill [V and the edger rolls [E,], which stage constitutes the abovementioned early stage ofrolling.

Having been discharged from the edger roll, the material is charged into the universal rolling mill [V then for rolling the part to be made into the head, the material is charged into the edger roll [E having the vertical roll and the vertical roll, thereby overcoming such difficulties as mentioned above in connection with rolling operations, and giving strong forging to the part of the material to be made into the head, particularly of a rail which is required to meet severe operating conditions.

I claim:

1. In a method for rolling by the universal rolling mill steel material into shaped steel products having flanges such as rails and H-shaped articles, the improvement comprising subjecting the part of said material to be made into a flange to a first rolling operation by a first vertical roll concentration of reduction force to the center of said part while preventingsubstantial restriction of extension of said part in the width direction thereof, thereby preventing the formation of an unforged zone of said part; subjecting said part to a second rolling operation by a second vertical roll of said universal rolling mill including imparting a smoothing reduction force to said part while increasing the restriction of extension of said part in the width direction thereof; and subjecting said part to a third rolling operation by a third vertical roll of said universal rolling mill including imparting a further smoothing reduction force to said part while further increasing the restriction of extension of said part in the width direction thereof.

2. In a universal rolling mill for rolling steel material into shaped steel products having flanges such as rails and H shaped articles, the improvement comprising a first vertical roll adapted to contact that part of said material to be made into a flange, said first vertical roll having a convex portion around the periphery thereof adapted to impart a concentrated V-shaped reduction force to the center of said part, and concave portions on either side of said convex portion, the outward extensions of said concave portions forming curves having a lower rate of curvature than the corners of said part when finished, said curves adapted to prevent substantial restriction of extension of said part in the direction of the width thereof.

3. In a universal rolling mill as claimed in claim 2 the further improvement comprising a second vertical roll adapted to contact said part, said second vertical roll having curves similar to but having a higher rate of curvature than said curves of said first vertical roll.

4. In a universal rolling mill as claimed in claim 3, the further improvement comprising a third vertical roll adapted to contact said part, said third vertical roll having curves similar to but having a higher rate of curvature than said curves of said second vertical roll. 

1. In a method for rolling by the universal rolling mill steel material into shaped steel products having flanges such as rails and H-shaped articles, the improvement comprising subjecting the part of said material to be made into a flange to a first rolling operation by a first vertical roll concentration of reduction force to the center of said part while preventing substantial restriction of extension of said part in the width direction thereof, thereby preventing the formation of an unforged zone of said part; subjecting said part to a second rolling operation by a second vertical roll of said universal rolling mill including imparting a smoothing reduction force to said part while increasing the restriction of extension of said part in the width direction thereof; and subjecting said part to a third rolling operation by a third vertical roll of said universal rolling mill including imparting a further smoothing reduction force to said part while further increasing the restriction of extension of said part in the width direction thereof.
 2. In a universal rolling mill for rolling steel material into shaped steel products having flanges such as rails and H-shaped articles, the improvement comprising a first vertical roll adapted to contact that part of said material to be made into a flange, said first vertical roll having a convex portion around the periphEry thereof adapted to impart a concentrated V-shaped reduction force to the center of said part, and concave portions on either side of said convex portion, the outward extensions of said concave portions forming curves having a lower rate of curvature than the corners of said part when finished, said curves adapted to prevent substantial restriction of extension of said part in the direction of the width thereof.
 3. In a universal rolling mill as claimed in claim 2 the further improvement comprising a second vertical roll adapted to contact said part, said second vertical roll having curves similar to but having a higher rate of curvature than said curves of said first vertical roll.
 4. In a universal rolling mill as claimed in claim 3, the further improvement comprising a third vertical roll adapted to contact said part, said third vertical roll having curves similar to but having a higher rate of curvature than said curves of said second vertical roll. 